What is Servomechanism: Servo System Definition, History, Components & Applications

Servomechanisms, or servo systems, historical evolution, from simple mechanical devices to complex electronic systems, mirrors the technological advancements of our society.

Initially conceived for naval fire control, the servomechanism has evolved into an indispensable component of modern machinery, robotics, and even consumer electronics where precision control is paramount.

What is a Servomechanism?

А servo mechanism, also known as servo system, and often shortened to “servo,” represents an automated control system capable of adjusting the output based on the feedback it receives, thereby achieving unparalleled accuracy in controlling an object’s position, speed, and overall movement.

A servomechanism is fundamentally a feedback control system that includes sensors, a controller, and actuators.

The sensors measure the position or speed of an object and send this information to the controller, which processes it and determines the necessary adjustments.

The actuators, often in the form of servomotors, then execute these adjustments to align the actual output with the desired output.

This closed-loop control is crucial in applications requiring precision, such as robotics, aerospace, and manufacturing machinery.

The beauty of a servomechanism lies in its ability to correct errors in real-time. This is achieved through negative feedback, where the system constantly compares the desired action with the actual action and minimizes the error between them.

This process of continuous adjustment is what allows servomechanisms to maintain precise control over the mechanisms they govern, making them indispensable in modern technology.

What is the History of Servomechanism?

The history of the servomechanism concept can be traced back to 18th century. 

The timeline below highlights the major milestones in the evolution of servomechanisms, showcasing their growing importance in a wide array of applications.

  • 1745: The concept of feedback, which is central to servomechanisms, was first introduced by James Watt in the design of the steam engine governor, an early form of a mechanical servo system.
  • 1868: The first electrical servo mechanism was developed by J.C. Maxwell for the position control of ship rudders, marking a significant advancement in navigational aids.
  • 1930s: The development of electronic amplifiers led to significant advancements in servo technology, enabling more precise and responsive control systems.
  • 1940s: During World War II, servomechanisms were extensively used in military applications, including gun laying and fire control systems, demonstrating their potential in high-stakes environments.
  • 1950s: The integration of servomechanisms into industrial machines revolutionized manufacturing processes, leading to the development of the first numerically controlled (NC) machines.
  • 1960s: The space race catalyzed the development of sophisticated servo systems for rocket and satellite positioning, showcasing their reliability and performance in extreme conditions.
  • 1970s: Advancements in microelectronics and digital control systems further expanded the capabilities of servomechanisms, enabling their integration into more complex and compact systems.
  • 1980s to Present: The proliferation of computers and digital technology has seen servomechanisms become integral to a vast range of applications, from robotics and medical devices to renewable energy systems and beyond.

How Do Servomechanisms Work?

Going deeper into the functioning of servomechanisms reveals a complex interplay of components and principles.

At its heart, the servomechanism operates on the basis of closed-loop control systems, distinguished by their ability to use feedback to regulate themselves.

The principle of operation behind a servomechanism is encapsulated in the concept of feedback and control. 

A servomechanism typically comprises a sensor for measuring the output, a controller for processing this information and determining the appropriate response, and an actuator for executing the response.

This setup allows the system to constantly adjust its actions based on the feedback received, ensuring that the output closely aligns with the input command.

Open Loop vs. Closed Loop Systems

Distinguishing between open loop and closed loop systems is essential in grasping the essence of servomechanism functionality. 

Both systems play a crucial role in the control theory, yet they operate on fundamentally different principles.

  • Open Loop Systems lack feedback mechanisms. Once an action is initiated, it continues without monitoring its effect. These systems are simpler but less accurate, as they cannot compensate for disturbances or changes in conditions.
  • Closed Loop Systems, the basis of servomechanisms, incorporate feedback, allowing the system to adjust its actions based on the outcomes. This constant adjustment loop significantly enhances accuracy, adaptability, and performance.

Advantages and Disadvantages

  • Open Loop Systems are straightforward and cost-effective but fall short in precision and adaptability.
  • Closed Loop Systems excel in accuracy and control but are more complex and expensive.

Understanding Feedback Loops

The heart of a servomechanism’s functionality lies in its feedback loop, a system designed to minimize errors by continuously adjusting actions based on feedback.

It involves the comparison of the actual output with the desired output to generate an error signal. This error signal is then used to adjust the system’s behavior, reducing the discrepancy between the actual and desired states.

Types of Feedback Used

Feedback mechanisms can be categorized based on the type of feedback they utilize, such as position feedback, speed control, or error correction signals.

  • Position Feedback: Monitors and adjusts the position of an output device to match the desired input command.
  • Speed Control Feedback: Ensures the velocity of the system’s movement aligns with the set parameters.
  • Error Correction Signals: Identify discrepancies between desired and actual outcomes, initiating corrective measures.

Mechanical Inertia and Its Effects on Servomechanisms

Inertia, the resistance of an object to change in its state of motion, significantly impacts the performance of servomechanisms. 

This physical principle affects how quickly and accurately a system can respond to control signals, especially in systems with high speeds or heavy loads.

  • Challenges Posed by Inertia: Increased demand on motors and control systems, potential delays in response times, and difficulties in maintaining precision.
  • Mitigating Inertia’s Impact: Systems are designed with considerations for the inertia of moving parts, employing advanced algorithms and compensatory mechanisms to counteract these effects.

Overcoming Overshoot and Hunting in Servomechanisms

Overshoot and hunting represent challenges where the system exceeds its target (overshoot) or oscillates around it (hunting). Addressing these issues is crucial for the stability and accuracy of servomechanisms.

Strategies and Mechanisms

  • Tuning of Control Parameters: Adjusting the gain settings of the controller to minimize oscillations and prevent overshoot.
  • Implementing Damping Techniques: Utilizing mechanical or electronic damping to absorb excessive energy and stabilize the system.
  • Advanced Control Algorithms: Employing sophisticated algorithms that anticipate and compensate for potential overshoot and hunting.

Error Detection and Correction

A critical aspect of servomechanism operation is the detection and correction of errors. This is achieved through error detectors and controllers that process the feedback from sensors and generate command signals for the actuators. The precision of a servomechanism hinges on its ability to quickly detect errors and implement corrective actions, ensuring the system remains on course.

Through the integration of sensors, controllers, and actuators, servomechanisms master the art of precision control. They exemplify the harmony between mechanical and electronic components, enabling the creation of sophisticated systems that can perform complex tasks with high accuracy and reliability. As such, servomechanisms have become foundational in the development of advanced automation and robotics solutions, driving innovation and efficiency across a multitude of industries.

What are the Components of a Servomechanism?

The precision and efficiency of a servomechanism depends on its components. Each part plays its role in ensuring the system’s functionality and reliability.

Below is an overview of these essential components, shedding light on how they come together to form a cohesive and effective servomechanism.

  • Servo Motor: The muscle of the servomechanism, a servo motor translates electrical signals into motion.
  • Servo Drivers and Amplifiers: A servo drive acta as the bridge between the controller and motor, modulating power to the motor based on the control signals.
  • Servo Controller: The system’s brain, a servo control processes input signals and navigates the movement of the motor.
  • Encoders: Provide feedback to the controller by tracking the position or speed of the motor shaft.
  • Servo Transmission Systems: Include gears and belts that amplify the motor’s movement to the required level.
  • Mechanical Housing: Protects the servomechanism’s components from external conditions, ensuring durability and longevity.

Servo Motor

Servo motors are integral to servomechanisms, offering precise control over motion. These motors are characterized by their ability to operate efficiently across a wide range of speeds and positions, facilitated by their design and the feedback mechanisms employed. Types of servo motors include:

  • AC Servo Motors: Ideal for applications requiring high accuracy and efficiency.
  • DC Servo Motors: Known for their quick response and high torque at low speeds.

Servo Drivers and Amplifiers

Servo drivers and amplifiers are crucial for translating control signals into actionable power for the servo motor. They regulate the voltage and current supplied to the motor, enabling precise control over its speed and position. The functionality of these components includes:

  • Signal Amplification: Boosting the control signals to levels sufficient to drive the motor.
  • Feedback Analysis: Utilizing feedback from encoders to adjust the power output, ensuring the motor’s motion aligns with the command signals.

Servo Controller

The servo controller orchestrates the operation of the servomechanism. It interprets the input commands, such as position or speed, and generates appropriate control signals for the servo drivers and amplifiers. This component is vital for:

  • Precision Control: Managing the detailed aspects of the servo motor’s operation.
  • Feedback Integration: Incorporating feedback from encoders to refine and adjust control signals in real-time.

Encoders in Servomechanisms

Encoders are indispensable for feedback in servomechanisms, providing critical data on the motor’s position or speed. This feedback allows the servo controller to make informed adjustments to the motor’s operation, ensuring high precision and accuracy. Encoders come in various types, including:

  • Incremental Encoders: Offer relative position information, useful for speed feedback.
  • Absolute Encoders: Provide precise location information, crucial for applications requiring exact positioning.

Servo Transmission Systems

Transmission systems in servomechanisms, such as gears and belts, are responsible for translating the motor’s rotation into the desired motion or force. These components are essential for:

  • Motion Amplification: Enhancing the movement produced by the servo motor to meet application requirements.
  • Flexibility in Configuration: Allowing for various mechanical arrangements to suit specific tasks.

Mechanical Housing

The mechanical housing ensures the servomechanism’s components are shielded from environmental factors that could impair their function or durability. It plays a critical role in:

  • Protection: Guarding against dust, moisture, and mechanical impact.
  • Heat Dissipation: Facilitating the removal of heat generated by the motor and electronics, preventing overheating.

What are Key Parameters and Performance Metrics for a Servo Mechanism (System)?

Understanding, measuring and optimizing servomechanism performance and parameters is a necessity for every operation.

Let’s go into the fundamental parameters and performance metrics that define the operation of servo mechanisms.

Torque and Rotational Speed

Two of the most vital parameters in servo systems are torque and rotational speed, each playing a pivotal role in the system’s performance.

  • Torque: This refers to the force that the servo motor can apply to turn an object. It is a crucial factor in applications requiring the movement of heavy loads or the exertion of significant force.
  • Rotational Speed: Also known as RPM (revolutions per minute), this measures how fast the servo motor can rotate. High rotational speeds are essential for tasks that require rapid movement.

Inertia Ratio

The inertia ratio is a critical factor in the design and functionality of servo mechanisms. It is the ratio of the load inertia to the motor inertia. A well-balanced inertia ratio is crucial for:

  • Optimal Performance: Ensuring the servo system is responsive and capable of precise control.
  • Energy Efficiency: Reducing energy consumption by minimizing the discrepancy between load and motor inertia.

Understanding and managing the inertia ratio is fundamental in achieving a balance between responsiveness and stability in servo mechanism operations.

Resolution and Precision

In the context of servo mechanisms, resolution and precision are paramount for accuracy. These metrics are significantly influenced by the encoders used in the system.

  • Resolution: Defined as the smallest movement the servo system can detect or command. Higher resolution equates to finer control and greater detail in movement.
  • Precision: Refers to the system’s ability to repeat movements with minimal variance. It is critical in applications where consistency and accuracy are non-negotiable.

Bandwidth and Frequency Response

Bandwidth and frequency response are key indicators of how quickly a servo system can respond to control inputs and how effectively it can manage changes in load or speed.

  • Bandwidth: This parameter represents the range of frequencies over which the system can operate effectively. A wider bandwidth allows for quicker response to changes, making the system more agile.
  • Frequency Response: Measures how well the servo system can follow rapid changes in command signals. It’s a critical factor in dynamic applications where speed and direction change frequently.

Understanding the bandwidth and frequency response of a servo system is vital in optimizing its performance, particularly in applications that demand quick reactions to varying conditions.

What are the Applications of Servomechanisms?

Servomechanisms, with their precise control over motion and force, have countless applications across various industries. 

From the movements required in robotics to the precision needed in manufacturing

Below we we will explore the broad range of applications where servomechanisms make a significant impact.

Position Control Applications

Position control stands as a cornerstone application of servomechanisms, where precise movement and placement are paramount. Here are six key examples:

  • Robotics: Servos ensure the accurate movement of robotic arms, enabling tasks from assembly to surgery.
  • Antenna Positioning: Critical in communication systems, servos adjust antenna angles for optimal signal reception and transmission.
  • Telescope Positioning: Astronomical observations rely on servomechanisms for the precise positioning of telescopes.
  • 3D Printing: Servos control the movement of the print head, laying down materials with exact precision.
  • CNC Machines: In machining, servos maneuver tools and materials to achieve intricate designs and shapes.
  • Automated Guided Vehicles (AGVs): For navigation and positioning within warehouses and factories, servos are indispensable.

Speed Control Applications

Controlling speed with high precision is another domain where servomechanisms excel. Here are six applications that depend on this capability:

  • Conveyor Systems: In manufacturing and logistics, servos regulate conveyor speeds to match production flows.
  • Pump and Fan Control: Servomechanisms adjust the speed of pumps and fans in response to system demands, optimizing energy use.
  • Electric Vehicles: Servos modulate the speed of electric motors, contributing to the efficiency and performance of EVs.
  • Machine Tools: Speed control in lathes and mills ensures material is removed at optimal rates, improving quality and efficiency.
  • Textile Machinery: In textiles, servos control the speed of spinning and weaving machines for consistent fabric production.
  • Mixing and Agitation Equipment: Precise speed control by servos ensures homogeneous mixing in chemical and food processing.

Other Unique Applications

Servomechanisms also find their place in less conventional, yet innovative applications. Here are six examples showcasing their versatility:

  • Camera Stabilization: In film and photography, servos stabilize cameras, compensating for movement to produce clear images.
  • Art Installations: Interactive art often utilizes servos for dynamic movement and engagement with viewers.
  • Medical Devices: From prosthetics to diagnostic machines, servos enable precise movements and adjustments.
  • Flight Simulators: For realistic training environments, servos create motion and force feedback, mimicking actual flight conditions.
  • Window and Ventilation Control: In smart buildings, servos adjust windows and vents for optimal environmental conditions.
  • Agricultural Equipment: Precision farming equipment uses servos for tasks like planting seeds at specific intervals and depths.

How to Choose the Right Servomechanism for Your Application?

Selecting the appropriate servomechanism for a specific application is a critical decision that significantly affects the performance and efficiency of your system. 

Understanding Your Application Requirements

The first step in selecting a servomechanism is comprehensively understanding the requirements of your application, including:

  • Position or Speed Control: Determine whether your application primarily requires precise position control, speed regulation, or both.
  • Load Characteristics: Assess the weight and inertia of the load the servo will move. This will influence the torque and power requirements.
  • Operating Environment: Consider the environmental conditions, such as temperature, humidity, and exposure to contaminants, which could affect the servo’s performance and durability.
  • Precision and Accuracy Needs: Evaluate the level of precision and accuracy required, as this will impact the choice of servomotors and feedback systems.

Evaluating Servo Mechanism Specifications

Once you have a clear understanding of your application’s requirements, you can begin evaluating specific servo mechanism specifications, including:

  • Torque and Speed: Choose a servo with the necessary torque and speed capabilities to handle your application’s load and operational pace.
  • Feedback Systems: Look for servos equipped with high-resolution encoders if your application demands high precision and accuracy.
  • Control Systems: Consider the compatibility of the servo with existing control systems or any specific control features you may need.
  • Mechanical Interface: Ensure that the physical dimensions and mounting options of the servo are compatible with your equipment.

Long-Term Considerations

Beyond immediate technical specifications, consider long-term factors that could affect the performance and cost-effectiveness of your servomechanism:

  • Durability and Reliability: Opt for servos known for their durability and reliability, especially in demanding or critical applications.
  • Support and Maintenance: Consider the level of technical support and ease of maintenance offered by the servo manufacturer.
  • Cost: While not the only factor, the cost of the servomechanism should align with your budget and the expected return on investment.

Consult with Experts

Finally, when selecting a servomechanism, it’s often beneficial to consult with experts or the manufacturers themselves. They can provide valuable insights into the nuances of servo performance and help tailor your selection to your specific needs.

As a leading manufacturer of servo drives and controllers that has built and shipped nearly 3 million servo axes worldwide, Advanced Motion Controls is always ready to give you advice on how to choose the right components for your servo system. Feel free 

What are Common Challenges and Solutions Related to Servomechanisms?

Servo systems can encounter a variety of challenges. Identifying these challenges and implementing effective solutions is crucial for maintaining the operational efficiency and reliability of servo systems.


One prevalent issue with servomechanisms is overheating, which can lead to system failure or degraded performance over time.

  • Causes:
    • Continuous operation beyond the system’s thermal capacity.
    • Inadequate cooling or ventilation.
  • Solutions:
    • Incorporating active cooling systems, such as fans or heat sinks.
    • Implementing duty cycles to allow for cooling periods.
    • Designing the system with thermal management in mind from the outset.

Feedback Signal Noise

Feedback signal noise can significantly affect the accuracy and stability of servomechanisms.

  • Causes:
    • Electromagnetic interference from nearby equipment.
    • Poorly shielded or grounded cables.
  • Solutions:
    • Using shielded cables for all signal wiring.
    • Improving system grounding.
    • Implementing filters to mitigate noise in the feedback signals.

Mechanical Wear

The mechanical components of servomechanisms can wear over time, affecting performance and necessitating repairs or replacements.

  • Causes:
    • Friction between moving parts.
    • Lack of regular maintenance.
  • Solutions:
    • Regular lubrication and inspection of mechanical components.
    • Using wear-resistant materials where possible.
    • Implementing a preventative maintenance schedule.

Inaccurate Positioning

Achieving and maintaining accurate positioning is critical for many applications of servomechanisms, and inaccuracies can arise from several sources.

  • Causes:
    • Backlash in the mechanical transmission elements.
    • Non-linearities or drift in the feedback system.
  • Solutions:
    • Minimizing backlash with precision gears or using backlash compensation techniques.
    • Calibrating the feedback system regularly to account for any drift.
    • Utilizing high-resolution encoders.

Insufficient Torque

Insufficient torque results in the servo’s inability to move the load as required, leading to underperformance or system stalling.

  • Causes:
    • Underestimating the load’s inertia or friction.
    • Servo motor undersized for the application.
  • Solutions:
    • Conducting a thorough analysis of the load requirements before selecting the servo motor.
    • Considering the use of gear reduction to increase effective torque.
    • Ensuring the power supply can deliver sufficient current for peak torque demands.

Electrical Noise Interference

Electrical noise can interfere with the control signals of servomechanisms, leading to erratic behavior or control inaccuracies.

  • Causes:
    • Electromagnetic interference from power lines or other electronic devices.
    • Ground loops in the electrical system.
  • Solutions:
    • Isolating sensitive signal paths from high-power circuits.
    • Implementing optical isolation for signal inputs and outputs.
    • Designing the system with proper grounding practices to avoid ground loops.


Servomechanisms play a critical role in modern automation, providing the precision and control required for complex and demanding applications. 

As technology advances, ongoing innovation in design, materials, and control strategies will further improve the performance and resilience of servomechanisms, solidifying their place at the forefront of automation technology.